Folding carton top with sequential locking flaps

ABSTRACT

A carton is disclosed with a simulated prewrap or gift wrapping in which the top is closed by means of four flaps which, when completely assembled, are self-locking and self-leveling. The preferred embodiment of the construction is employed with a simulated prewrap or gift wrap which extends in weblike fashion between three of the flaps and is secured to the flaps at a portion between the end of the flap and the junction between the flap and the carton.

United States Patent 1 i 1 I I Inventor Appl. No.

Filed Patented Aasignec Leonard Adams, Jr.

Louisville, Ky.

June 24, 1969 Nov. 1 6, i971 The Finn industries Division, Potlatch Forests, Inc.

Chicago, ill.

FOLDING CARTON TOP WITH SEQUENTIAL LOCKING FLAPS 10 Claims, 12 Drawing Figs.

US. Cl 229/39 R, 229/39 B, 229/87 R Int. Cl B65d 5/10 Field of Search 229/8, 39, 39 B, 87 M Reierences Cited UNITED STATES PATENTS 7/l933 6/l950 8/1960 6/1966 5/l969 Ancira Buerger Grisetti et al.

Wright Adams, Jr

Primary Examiner-Joseph R. Leclair Assistant Examiner-Steven E. Lipman Auorney Dominik, Knechtel & Godula 229/39 X 229/39 X 229/39 229/87 M 229/39 ABSTRACT: A carton is disclosed with a simulated prewrap or gift wrapping in which the top is closed by means of four flaps which, when completely assembled, are self-locking and v self-leveling. The preferred embodiment of the construction is employed with a simulated prewrap or gift wrap which extends in weblike fashion between three of the flaps and is secured to the flaps at a portion between the end of the flap and the junction between the flap and the carton.

PATENTEDuuv 16 197:

SHEET 1 BF 2 FIG. 2

IN VE N TOR Leonard Adams J flmmj l e'a q ATTYS.

PAIENTEUNHV 16 l97l SHEU 2 OF 2 FIG.

INVENTOR Leonard Adams I]? ATTYS.

FOLDING CARTON TOP WITH SEQUENTIAL LOCKING FLAPS The present invention relates to a folding carton, and more particularly a top thereof which is entitled FOLDING CAR- TON TOP WITH SEQUENTIAL LOCKING FLAPS. The invention finds preferred application with that type of gift wrapped carton having a simulated prewrap which is loosely wrapped around the body portion of the carton.

At the Holiday Season and other times of the year many manufacturers of spirits package their bottled products in folding cartons which are decorated and require no further wrapping as a present. Such cartons advantageously may employ a removable identification band such as shown in Bolding, U.S. Pat. No. 2,950,040. In those instances where highspeed expensive machines known as the Jones Machines are not installed and the carton is filled by hand, advantageously a self-leveling bottom may be employed of the character disclosed in my previous U.S. Pat. No. 3,443,739, issued Mar. 16, 1967. Since the carton with its contained bottle normally sits on the bottom, the customer purchasing the same as well as the person receiving it as a gift primarily views the top portion. Attempts have been made to render the tops of such cartons highly decorative and simulating substantially a hand-wrapped construction, such as shown in Margueritte Wright U.S. Pat. No. 3,257,068. The disadvantage of such constructions, while pleasing in appearance, is that the opposing flaps must be secured with a decorative bow, seal, or other securing means which is an additional step in operation, and also frequently requires expensive additional decorative members.

In view of the foregoing, it is a principal object of the present invention to provide a sequential folding interlocking top construction for use with a knocked-down or folding carton having a simulated prewrap which can be readily erected by hand, and self-levels itself into a locked top portion with no raw board exposed.

A related object of the present invention is to provide a sequential locking top for a folding carton which eliminates the need for a label or how with a prewrapped type construction for securing the top.

Still another and significant object of the present invention is to employ a top construction with a simulated prewrapped carton in which there is a substantial saving in the top construction of paperboard, as compared to some prior art constructions in the amount of 20 percent on a carton end which can amount to 3 percent on the overall requirements for the carton.

Still another detailed object of the present invention looks to the provision of a sequential folding self-locking top construction in which a portion of the top serves to prevent the subsequently inserted elements from dislodging the Federal tax stamp from the top of the bottle being packaged, the same often being placed into the carton while still wet and the glue securing the same to the top of the bottle has not set.

Still another detailed but important economic advantage of the carton of the present invention is achieved through the use of the top construction in conjunction with a self-leveling bottom in which both ends normally have coacting elements which flatten the ends even though hand-assembled.

Still another object of the present invention looks to the provision of a sequential locking top with a simulated prewrap in which there is no raw board exposed, and the end faithfully simulates hand wrapping.

Further objects and advantages of the present invention will become apparent as the following description of an illustrative embodiment proceeds, taken in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view illustrating the relationship between the carton and the contained bottle, the latter and its seal being shown in phantom lines.

FIG. 2 is a top view of the carton shown in FIG. 1 with the top closed.

FIG. 3 is a top perspective view of the carton with the flaps extended upwardly showing their relationship each to the other prior to closure.

FIG. 4 is a top perspective view similar to FIG. 3 showing the insertion of the first flap. 1

FIG. 5 is a top perspective view similar to FIG. 3 showing the sequential folding of the second flap and its coaction with the first flap.

FIG. 6 is a top perspective view similar to FIG. 3 of the sequential folding of the third'flap and its interrelationship with the first and second flaps.

FIG. 7 is a top perspective view similar to FIG. 3 of the folding of the last or fourth flap into place and its coaction with the preceding three flaps.

FIG. 8 is an enlarged partially diagrammatic view of the center portion of the top of the carton showing two of the end flaps in their closed position and the bottle cap and Federal taxstamp there beneath.

FIG. 9 is a subsequent sequential view of the enlarged center of the top as shown in FIG. 8 with the third flap shown therein illustrating how the lateral extension on the third flap fits atop the bottle and its Federal tax stamp so that the latter, if still wet and not permanently secured, is shielded against dislodgrnent by the lateral extension of the third flap.

FIG. 10 is a layout view of the board which forms the underbody for the top construction having broken away the body of the carton in the base portion.

FIG. 11 is a sequential view in manufacturing of the laid out carton top to the same scale as shown in FIG. 10, but illustrating the subsequent application of the simulated prewrap.

FIG. 12 is a view of the reverse side of the carton top as shown in FIG. 11 illustrating, however, the folded over relationship of the glue flap on one side, and the prewrap extensions beyond the remote edges of the body panels of the carton.

For an understanding of the advantages and the invention attention is invited to FIG. 1 where it will be seen that the carton 10 contemplates enclosing a bottle 11 by means of four side panels 12 which define a tubular body of the carton 10. The bottom 14 of the carton 10, as set forth above, is advantageously a self-forming, self-leveling bottom of the construction disclosed in my previous U.S. Pat. No. 3,443,739, issued Mar. 16, 1967. When employed with the carton 10 described in detail below, the carton is first opened to the configuration shown in FIG. 3, and the bottle 11 then is inserted, oftentimes while the Federal tax stamp 18 which is affixed to the bottle to seal it is still wet and hence subject to dislodgment. Thereafter, the top flaps are folded over sequentially to form the carton top 15, in the hereinafter described manner. When all of the top flaps have been folded, as shown in FIG. 2, to close the carton top 15, the carton 10 is enclosed, and the carton top 15, as well as the side panels 12, which are enclosed preferentially .in a loose wrapped prewrap 20, all have a neat gift-wrapped appearance.

The steps employed in hand closing the carton top 15 are best illustrated sequentially in FIGS. 4 through 7 inclusive. When the carton 10 is erected from its knocked-down configuration, the first, second, third and fourth top flaps 21, 22, 23, 24 all extend upwardly, as shown in FIG. 3. Three of these top flaps are connected by means of prewrap webs 40. The bottle 11 is slipped into the body portion of the carton l0 defined by the panels 12, while the top flaps 21-24 are still positioned, as shown in FIG. 3.

Thereafter, as illustrated in FIG. 4, the first top flap 21 is folded inwardly and, as the latter is folded, the prewrap web 40a (out of sight in FIG. 4) between the first top flap 21 and the second top flap 22 is folded downwardly along the diagonal edge 32 on the second top flap 22. The prewrap reverse flap 41 previously has been folded along the diagonal edge 31 on the first top flap 21 and is preferably affixed to the inside surface of the first top flap 21, as more fully described below. The second top flap 22 is then folded downwardly, as illustrated in FIG. 5. The prewrap web 404 now is sandwiched between the first and second top flaps 21 and 22, and the lateral extension 27 on the second top flap 22 lies closely adjacent the diagonal edge 31 of the first top flap 2]. (For reference see the enlarged showing in FIG. 8.) As this second top flap 22 is folded, the prewrap web 40b is folded downwardly along the diagonal edge 33 on the third top flap 23. Thereafter, the third top lap 23 is folded downwardly, as indicated in FIG. 6, and as this top flap is folded, the prewrap web 400 is folded over the diagonal edge 34 on the fourth top flap 24. The lateral extension 28 on the third top flap 23 is tucked in the slot 37 (FIGS. 8 and 9) defined between the edge of the lateral extension 27 on the second top flap 22 and the diagonal edge 31 of the first top flap 21. This lateral extension 28 on the third top flap 23, when tucked in the slot 37, extends inwardly and beneath the first top flap 21, particularly as illustrated in the enlarged showing in FIG. 9. Continuing to refer to FIG. 9, it will be seen there that the lateral extension 28 of the third top flap 23 in combination with the balance of the thus three-folded top flaps completely secures the Federal tax stamp 18 from any engagement by the locking action of the fourth top flap 24, which remains to be folded to secure the carton top 15, in the configuration illustrated in FIG. 2.

Turning now to FIG. 7, it will be seen that the fourth top flap 24 is folded, and thereafter locked in a closed position by extending its locking tab 30 beneath the diagonal edge 31 of the first top flap 21, and continuing to insert the same until the locking barb 35 thereon (FIGS. 10 and 11) engages beneath the central intersection of the first three top flaps. At this point, the locking barb 35 actually hooks underneath the upper edge of the second top flap 22, as the locking tab 30 slides into the slot 37 and beneath the first top fiap 21. After the closure is completed, the carton top 15, as indicated above, appears as shown in FIG. 2.

7 It will be appreciatedthat on an assembly line where the bottles are inserted into the carton 10 by hand, the cartons are delivered flat with the base or bottom 14 folded inwardly and sandwiched between the panel 12. The top flaps 21, 22, 23, 24 extend upwardly, as extensions of their respective panels 12. A score line 43 is formed between each of the top flaps 21, 22, 23, 24 and its associated panel 12, as shown in FIGS. 10 and 11. The provision of this score line permits the end flaps to be easily folded in sequential fashion, with the finger strength of the production worker.

In FIG. 10, the precut configuration of the underlying board portion of the carton 10 is shown. There it will be seen that the first top flap 21 has a diagonal edge 31 and a rectangular support tab 25. The edges 48 of the first three top flaps 21, 22, 23 are straight line extensions of the score lines between adjacent panels 12. The diagonal 31, in a carton having a square cross section, extends diagonally upwardly from the score line 45 joining the top flap to its associated panel 12 to a point substantially centrally of the width of a panel and spaced inwardly from its upper edge. It will be observed that this relationship is.

preserved in each of the top flaps 21, 22 and 23, although the diagonal edge 34 of the fourth flap 24 extends slightly thcrebeyond to define, in combination with the locking tab 30, the locking barb 35. In summary, therefore, each of the top flaps 21-24 has regularly formed diagonal edges 31-34, respectively, and the top flap 22 further is formed in a fashion such that its diagonal edge 32 terminates in a tab 26 having a lateral extension 27 which defines a V-notch 36. Similarly, the top flap 23 has a lateral extension 28 which is joined by a score line 29 to the balance of the top flap 23. The score line 29 is an extension of the diagonal edge 33 of the top flap 23, and defines a V-notch 38.

The top flap 24 differs from the top flaps 21-23 in that its edge 50, rather than being a straight edge like the straight edges 48, curves inwardly so as to define, in conjunction with the diagonal edge 34, the locking barb 35 which is slightly offset from the midpoint of the top flap 24. The score line 39 on the top flap 24 defines the locking tab 30 which, in the embodiment enclosed, is crescent-shaped. It will be appreciated that the exact configuration of the locking tab 30 of the top flap 24 may be varied in accordance with the usage intended, but essential to the invention is the provision of the locking barb 35 to secure the entire carton top in place.

Turning now to FIG. 11, it will be seen that the underlying board shown in FIG. 10 is substantially covered with a simulated prewrap 20 which overlaps the top flaps 21-24, to the extent that its upper edge intersects approximately the V- notches 36, 38 of the top flaps 22 and 23. This prewrap 20 can be loosely fitted to the side panels 12 and secured to the bottom flaps (not shown) and to the top flaps 21-24. Thus, when the carton top 15 is formed, the simulated prewrap 20 completely intersects at the center, and no exposed board is shown, as illustrated in FIG. 2. Nevertheless, the support tab 25 of top flap 21, the support tab 26 of the top fiap 22, the lateral extension 28 of the top flap 23, and the locking barb 35 of the top flap 24 are all exposed so that they can coact when the top flaps are folded, as illustrated in FIGS. 4 through 7 inclusive. It will be apparent that an adhesive can be applied to these extensions if positive sealing is desired, but in practice, the interlocking action of the locking barb 35 on the top fla'p 24 will be sufi'icient to lock the carton top.

From a manufacturing standpoint, it will be seen that the prewrap webs 40 extend between the straight edges 48 and all four diagonal edges 31, 32, 33, 34 of the next adjacent flap. Therefore, no special cutting or forming between the flaps is required.

As shown in FIG. 12, which is a reverse view of FIG. 11 prior to forming the carton 10, the prewrap extension running beyond the diagonal edge 31 of the top flap 2] is reversely folded along the diagonal edge 31 and secured to the inside of the top flap 21 to form a prewrapped reverse flap 41. Advantageously, particularly when employing the construction of Bolding U.S. Pat. No. 2,950,040, to provide a removable band for the carton, two glue flaps 42 are provided as lateral extensions of the outside panels 12, separated by score line 44 from the adjacent panels 12. The right glue flap 42 is reversely folded along the score line 44 and'glued against the adjacent panel 12. The prewrap extensions 45 are secured to these glue flaps, as illustrated. At the locking tab 30 of the top flap 24, the prewrap extension 45 extends in a rectilinear fashion from the glue flap 42 rather than curving over the curvilinear portion of the locking tab 30, although the latter is contemplated as possible. The reason for folding the curvilinear attachment is that it is not necessary in manufacture, and furthermore, any loose edge is hidden beneath the adjacent top flaps and therefore any economy in operation is achieved with conventional equipment. For example, not in FIG. 7 how the locking tab 30 of the top flap 24 fits beneath the diagonal edge 31 of the top flap 21 thereby hiding any loose prewrap edge 45 which was previously adjacent the locking tab 30.

In reviewing it will benoted particularly as to FIGS. 10 through 12 inclusive that the amount of board extending beyond the upper edge of the prewrap 20 is the absolute minimum required to providea closure and intersection at the center and is a small percentage of the top flap triangular height portion terminating at the V-notches 36, 38. The locking tab portions 25, 26, 28, 30 extending beyond the upper edge of the prewrap 20 is only sufficient to accomplish the interlock of the top closure 15 at the ends of the top flaps 21, 22, 23, 24. As set forth above, the saving in board providing this type of carton top can amount to 20 percent over altemative-type carton top constructions, and yet preserve not only a manual locking function, but prevent the dislodgment of the Federal tax stamp on the enclosed bottle, and still achieve a simulated prewrap end closure. Quite obviously, with a four-fingered action of both hands, operators can be trained to high-speed manual skill very quickly for the positioning of the bottles within the subject carton and closing the top flaps to form the carton top. Inasmuch as the amount of board is held to a minimum as set forth above, so is the amount of simulated prewrap 20 employed to enclose the entire carton 10 held to an irreducible minimum, since it is proportioned to intersect neatly at the locking portions of the top flaps of the carton.

It will thus be seen that the objects set forth above, among those made apparent from he preceding description, are efficiently attained and certain changes may be made in the above article. Accordingly, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Now that the invention has been described, what is claimed as new and desired to be secured by Letters Patent is:

1. in a folding carton having four side panels which are joined together to form a tubular carton body, an improved end closure comprising an end closure flap extending from and integrally affixed along a score line to each of the side panels; said end closure flaps having a diagonal edge which are parallel with one another in flat blank form and extend diagonally upwardly from said score line and terminate at a point disposed on a line extending substantially through the midpoint of the width of its associated side panel, said end closure flaps being sequentially folded in overlying relationship to close the top of said carton, the last folded end closure flap having a diagonal edge thereon which terminates at substantially the midpoint thereof, a score line extending from the terminus of said diagonal edge to its panel comer opposite the panel comer where the said diagonal edge originates, said score line defining on said end closure flap a locking tab and a locking barb at substantially the midpoint of the width thereof proportioned for interlocking fit beneath the midpoint of the widths of the first, second and third folded end closure flaps when the latter have been sequentially folded and the locking tab on the last folded end closure flap has been inserted beneath the diagonal edge of the first folded end closure flap, said first, second and third end closure flaps thereby being locked in overlapped relationship, to completely close the end of said carton.

2. In the folding carton of claim 1, a prewrap fitted to the side panels and secured to each of said end closure flaps, said prewrap overlapping said end closure flaps and extending substantially to the terminus of said diagonal edges thereon, said prewrap further extending in weblike form between said end closure flaps.

3. in the folding carton of claim 1, wherein said locking tab of said last folded end closure flap is crescent-shaped.

4. In a folding carton having four side panels which are joined together to form a tubular carton body, an improved end closure comprising an end closure flap extending from and integrally affixed along a score line to each of the side panels; said end closure flaps having a diagonal edge which are parallel with one another in flat blank form and extend diagonally upwardly from said score line and terminate at a point disposed on a line extending substantially through the midpoint of the width of its associated side panel, said end closure flaps being sequentially folded in overlying relationship to close the top of said canon, a support tab on the second folded one of said end closure flaps extending from the terminus of said diagonal edge thereon to the upper edge thereof, a lateral extension on said support tab defining a V-notch at the terminus of said diagonal edge, the third folded one of said end closure flaps having a support tab extension extending from the terminus of said diagonal edge thereon to the upper edged thereof, a score line forming a continuation of the diagonal edge on said third end closure flap defining said support tab, a lateral extension proportioned to overlie said lateral extension of the support tab on the second folded one of said end closure flaps and to tuck beneath said diagonal edge on the first folded end closure flap to partially lock the first, second and third folded end closure flaps in overlapped relationship, the last folded end closure flap having a locking tab, said locking tab being proportioned for an interlocking fit beneath said diagonal edge of the first folded end closure flap to thereby lock said last-folded end closure flap in overlapping relationship with the other ones of said end closure flaps, said other ones of said end closure flaps thereby also being locked in overlapped relationship, to completely close the end of said carton.

5. in a folding carton of claim 4, wherein said last folded end closure flap has a diagonal edge thereon which terminates at substantial y the midpoint thereof, a score line extending from the terminus of said diagonal edge to its panel comer opposite the panel comer where the said diagonal edge originates, said score line defining on said end closure flap said locking tab, and a locking barb at substantially the midpoint of said end closure flap proportioned for interlocking fit beneath the midpoint of the first, second and third folded end closure flaps when the latter have been sequentially folded and the locking tab on the last-folded end closure flap has been inserted beneath the diagonal edge of the first folded end closure flap.

6. in a folding carton having four side panels which are joined together to form a tubular carton body, an improved end closure comprising an end closure flap extending from each of the side panels; a first end closure flap having a diagonal edge and a support tab extending from the terminus of said diagonal edge to the upper edge of the first end closure flap; a second end closure flap having a diagonal edge and a support tab extending from the terminus of said diagonal edge to the upper edge of the second end closure flap, a lateral extension on said support tab defining a V-notch at the terminus of the diagonal edge on said second end closure flap; a third end closure flap having a diagonal edge and a support tab extension extending from the terminus of said diagonal edge to the upper edge of the third end closure flap, a score line on said third end closure flap forming a continuation of the diagonal edge on it, said score line defining on said support tab a lateral extension proportioned to overlie the lateral extension of the second end closure flap and to tuck beneath the diagonal edge of the first end closure flap to thereby partially lock the first, second and third end closure flaps in overlapped relationship when they are sequentially folded; and a fourth end closure flap having a locking tab thereon proportioned for an interlocking fit between the diagonal edge of the first end closure flap and the lateral extension of the third end closure flap to thereby lock said fourth end closure flap in overlapping relationship with other ones of said end closure flaps and to completely close the end of said carton.

7. In the folding carton of claim 7, wherein the diagonal edges on said end closure flaps extend diagonally upwardly and terminate at a point disposed on a line extending substantially through the midpoint of the width of their associated side panels.

8. In the folding carton of claim 6, wherein said fourth end locking closure flap has a diagonal edge extending from one of its panel comers and terminating substantially at a midpoint of the width thereof, a score line extending from the terminus of said diagonal edge to its panel corner opposite said panel comer where said diagonal edge originates, said score line defining on said end closure flap said locking tab, and a locking barb at substantially at the midpoint of the width of said fourth end closure flap proportioned for interlocking fit beneath the midpoint of the first three end closure flaps when the latter are sequentially folded and said locking tab is inserted beneath the diagonal edge of the first end closure flap.

9. in the folding carton of claim 6, a prewrap fitted to the side panels and secured to each of said end closure flaps, said prewrap overlapping said end closure flaps and extending substantially to the tenninus of said diagonal edges thereon, said prewrap further extending in weblike form between said end closure flaps.

10. in the folding carton of claim 6, wherein said locking tab of said fourth end closure flap is crescent-shaped.

* l i i 

1. In a folding carton having four side panels which are joined together to form a tubular carton body, an improved end closure comprising an end closure flap extending from and integrally affixed along a score line to each of the side panels; said end closure flaps having a diagonal edge which are parallel with one another in flat blank form and extend diagonally upwardly from said score line and terminate at a point disposed on a line extending substantially through the midpoint of the width of its associated side panel, said end closure flaps being sequentially folded in overlying relationship to close the top of said carton, the last folded end closure flap having a diagonal edge thereon which terminates at substantially the midpoint thereof, a score line extending from the terminus of said diagonal edge to its panel corner opposite the panel corner where the said diagonal edge originates, said score line defining on said end closure flap a locking tab and a locking barb at substantially the midpoint of the width thereof proportioned for interlocking fit beneath the midpoint of the widths of the first, second and third folded end closure flaps when the latter have been sequentially folded and the locking tab on the last folded end closure flap has been inserted beneath the diagonal edge of the first folded end closure flap, said first, second and third end closure flaPs thereby being locked in overlapped relationship, to completely close the end of said carton.
 2. In the folding carton of claim 1, a prewrap fitted to the side panels and secured to each of said end closure flaps, said prewrap overlapping said end closure flaps and extending substantially to the terminus of said diagonal edges thereon, said prewrap further extending in weblike form between said end closure flaps.
 3. In the folding carton of claim 1, wherein said locking tab of said last folded end closure flap is crescent-shaped.
 4. In a folding carton having four side panels which are joined together to form a tubular carton body, an improved end closure comprising an end closure flap extending from and integrally affixed along a score line to each of the side panels; said end closure flaps having a diagonal edge which are parallel with one another in flat blank form and extend diagonally upwardly from said score line and terminate at a point disposed on a line extending substantially through the midpoint of the width of its associated side panel, said end closure flaps being sequentially folded in overlying relationship to close the top of said carton, a support tab on the second folded one of said end closure flaps extending from the terminus of said diagonal edge thereon to the upper edge thereof, a lateral extension on said support tab defining a V-notch at the terminus of said diagonal edge, the third folded one of said end closure flaps having a support tab extension extending from the terminus of said diagonal edge thereon to the upper edge thereof, a score line forming a continuation of the diagonal edge on said third end closure flap defining said support tab, a lateral extension proportioned to overlie said lateral extension of the support tab on the second folded one of said end closure flaps and to tuck beneath said diagonal edge on the first folded end closure flap to partially lock the first, second and third folded end closure flaps in overlapped relationship, the last folded end closure flap having a locking tab, said locking tab being proportioned for an interlocking fit beneath said diagonal edge of the first folded end closure flap to thereby lock said last-folded end closure flap in overlapping relationship with the other ones of said end closure flaps, said other ones of said end closure flaps thereby also being locked in overlapped relationship, to completely close the end of said carton.
 5. In a folding carton of claim 4, wherein said last folded end closure flap has a diagonal edge thereon which terminates at substantially the midpoint thereof, a score line extending from the terminus of said diagonal edge to its panel corner opposite the panel corner where the said diagonal edge originates, said score line defining on said end closure flap said locking tab, and a locking barb at substantially the midpoint of said end closure flap proportioned for interlocking fit beneath the midpoint of the first, second and third folded end closure flaps when the latter have been sequentially folded and the locking tab on the last-folded end closure flap has been inserted beneath the diagonal edge of the first folded end closure flap.
 6. In a folding carton having four side panels which are joined together to form a tubular carton body, an improved end closure comprising an end closure flap extending from each of the side panels; a first end closure flap having a diagonal edge and a support tab extending from the terminus of said diagonal edge to the upper edge of the first end closure flap; a second end closure flap having a diagonal edge and a support tab extending from the terminus of said diagonal edge to the upper edge of the second end closure flap, a lateral extension on said support tab defining a V-notch at the terminus of the diagonal edge on said second end closure flap; a third end closure flap having a diagonal edge and a support tab extension extending from the terminus of said diagonal edge to the upper edge of the third eNd closure flap, a score line on said third end closure flap forming a continuation of the diagonal edge on it, said score line defining on said support tab a lateral extension proportioned to overlie the lateral extension of the second end closure flap and to tuck beneath the diagonal edge of the first end closure flap to thereby partially lock the first, second and third end closure flaps in overlapped relationship when they are sequentially folded; and a fourth end closure flap having a locking tab thereon proportioned for an interlocking fit between the diagonal edge of the first end closure flap and the lateral extension of the third end closure flap to thereby lock said fourth end closure flap in overlapping relationship with other ones of said end closure flaps and to completely close the end of said carton.
 7. In the folding carton of claim 7, wherein the diagonal edges on said end closure flaps extend diagonally upwardly and terminate at a point disposed on a line extending substantially through the midpoint of the width of their associated side panels.
 8. In the folding carton of claim 6, wherein said fourth end locking closure flap has a diagonal edge extending from one of its panel corners and terminating substantially at a midpoint of the width thereof, a score line extending from the terminus of said diagonal edge to its panel corner opposite said panel corner where said diagonal edge originates, said score line defining on said end closure flap said locking tab, and a locking barb at substantially at the midpoint of the width of said fourth end closure flap proportioned for interlocking fit beneath the midpoint of the first three end closure flaps when the latter are sequentially folded and said locking tab is inserted beneath the diagonal edge of the first end closure flap.
 9. In the folding carton of claim 6, a prewrap fitted to the side panels and secured to each of said end closure flaps, said prewrap overlapping said end closure flaps and extending substantially to the terminus of said diagonal edges thereon, said prewrap further extending in weblike form between said end closure flaps.
 10. In the folding carton of claim 6, wherein said locking tab of said fourth end closure flap is crescent-shaped. 